it's a P4 skt 478 board with AGP 4x, you'll be hard pressed to find a 4x AGP card these days, if your slot is AGP 2.0 an 8x card will run in it, if it is AGP 3.0 an 8x card may run in it
Read this
EDIT: After a little more searching I found that it is AGP 2.0 so an 8x AGP card should run in it:
AGP Bus(es) on Hub 1
Version : 2.00
Speed : 4x 90MHz (360MHz data rate)
Multiplier : 1/2x